Over a century of industrial development and operations has created a legacy of significant contamination in adjoining water bodies and underlying sediments of historic industrial sites. Sediment remediation presents unique challenges compared with remediation of upland (onshore) sites. Remediation technologies developed for upland sites have been found to have limited applicability to contaminated sediment sites, primarily due to the aqueous environment in which the contaminated sediments are found. More importantly, the volumes of contaminated media present at sediment sites requiring remediation can be orders of magnitude greater than that which exists at contaminated upland sites resulting in extensive cleanup time and costs due to technological limitations. The United States Environmental Protection Agency (EPA) has identified many sediment and upland sites impacted by organic hydrocarbons, polycyclic chlorinated biphenyls, dioxins, and other environmental contaminants that require remediation.
Current methods of sediment remediation typically require that sediments first be dredged and then transported to facilities for dewatering, after which they must be hauled to a regulated waste disposal facility. Due to the volumes of sediments requiring dredging, dewatering and disposal at the larger sites, cleanup times for such sites using existing technologies have extended to ten years or greater with associated costs in the hundreds of millions to over a billion dollars. Local internment leaves the contaminants in place and is being considered as a cost savings alternative to disposal at regulated waste disposal facilities. However, there is often insufficient space within the area under remediation to construct such a unit and public opinion on such local internment sites is generally highly negative.
Similarly, the remediation of contaminated upland sites generally occurs through the excavation of the impacted soils. It situ and ex situ technologies have been applied to remove and/or degrade the contaminants on the soil, however with limited success and at times prohibitive costs. Therefore, disposal of these excavated soils at a regulated waste disposal facility is still a common practice.
Thus, a method for desorption of contaminates and treatment of contaminated sediments and soils that a) is continuous or semi-continuous in nature, b) has a high throughput capacity, c) is cost effective, and d) incorporates attributes of “green” and sustainable technologies would revolutionize the remediation field.